Escapable commas in CLI options?

[npetruzzelli]

The commander argument parser for the --ignore option:

react-docgen/packages/react-docgen-cli/src/commands/parse/command.ts

Lines 26 to 39 in f5d644a

	function collect(value: string, previous: string[]): string[] {
	if (
	!previous ||
	previous === defaultIgnoreGlobs ||
	previous === defaultHandlers ||
	previous === defaultResolvers
	) {
	previous = [];
	}
	const values = value.split(',');
	return previous.concat(values);
	}

react-docgen/packages/react-docgen-cli/src/commands/parse/command.ts

Lines 62 to 67 in f5d644a

	.option(
	'-i, --ignore <glob>',
	'Comma separated list of glob patterns which will ignore the paths that match. Can also be used multiple times.',
	collect,
	defaultIgnoreGlobs,
	)

... splits on a comma, which makes it impossible to use glob brace expansion for this option or commas in general for any option that also uses this argument parser.

---

Would supporting escapable commas be possible?

---

To avoid breaking changes you may need to make it opt-in (behind a new option --comma-escaping or similar.)

The problem seems common enough and has been solved different ways in different languages. Here is a rough first pass after a little (very little) research:

/**
 * Split on commas (","), unless they are escaped with a backslash("\,").
 *
 * Escaped commas are replaced with individual commas.
 */
export function splitOnComma(str: string): string[] {
  if (typeof str !== 'string') {
    const errorMessage = 'input must be a string'
    throw new TypeError(errorMessage)
  }
  const DELIMETER = ','
  const ESCAPE_CHAR = '\\'
  const ESCAPED_DELIMETER = ESCAPE_CHAR + DELIMETER
  const hasEscapedDelimeter = str.includes(ESCAPED_DELIMETER)

  // Negative Lookbehind: https://www.regular-expressions.info/lookaround.html
  const result = str.split(/,(?<!\\,)/)

  if (hasEscapedDelimeter) {
    return result.map((subStr) => subStr.replace(/\\,/gi, DELIMETER))
  }
  return result
}

I don't have experience with negative lookbehinds. I wrote the example to favor being excessively self-documenting. Refinements could include:

• improved error message
• reducing the number of lines needed
• adding unit tests
• if the build tools are configured for ES2021+, String.prototype.replaceAll could be used instead.
  • subStr.replaceAll(ESCAPED_DELIMETER, DELIMETER))
• perform the replacement in fewer operations / general performance improvement

[npetruzzelli]

In fairness, a counter argument:

This only seems to affect "lists" within brace expansion, and something similar can be accomplished with the Regex Groups syntax

• https://github.com/mrmlnc/fast-glob?tab=readme-ov-file#advanced-syntax
• https://github.com/micromatch/micromatch?tab=readme-ov-file#matching-features
• https://github.com/micromatch/braces?tab=readme-ov-file#why-use-braces